Mario, Luigi, Starlow, and Prince Dreambert all need a tour guide up the mountain and Lil' Massif says that his older brother Big Massif is the only one who can do it. Mario and Luigi eventually find Big Massif sleeping on a Dreampoint where it was revealed that he can get tougher training in the dream world. Luigi then sleeps beside Big Massif while Mario enters into Luigi's dreams to find Big Massif. Mario and Dreamy Luigi then walk around in Dreamy Wakeport until they run into the tour guide receptionist. He tells Mario and Dreamy Luigi that they must complete the Beef-Off first and they do so. It was then revealed that the receptionist was Big Massif himself all along and challenges Mario and Dreamy Luigi to a fight. He ends up losing and realizes that he can get stronger in the real world and leaves out of his dreams.
Big Massif fights very similar to the Hooraws except he is much stronger. Big Massif always summon other Hooraws to his side and attacks mainly by chucking rocks at Mario and Dreamy Luigi. He can also toss himself at Mario dealing damge and use a Hermite Crab to distract Mario and charge at him. Once half of his HP is gone, Big Massif will then use a move similar to the Luiginary Stack, but Mario has to dodge the hooraws and the shockwaves that come from the landing. Big Massif gets angry and gains a power boost everytime Hooraws are defeated. He has three stages of anger depending of the number of Hooraws who are beaten, each one giving him a bigger power boost than the last. He usually calms down and loses his boost after his turn.
Big Massif has a lot of HP and hits very hard so it is very wise to stock up on Super Mushrooms, Syrups, and Candies. Using Luiginary Moves is also a must to deal high damage very quickly but every time a group of Hooraws is beaten, Big Massif's POW will go up making him more and more powerful.